TWI674679B - Foil-based metallization of solar cells - Google Patents

Abstract

A method for foil-based metallization of a solar cell and the resulting solar cell are described. In one example, a solar cell includes a substrate. A plurality of alternating N-type and P-type semiconductor regions are disposed in or on the substrate. The conductive contact structure is disposed on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions providing metal seed material regions disposed on each of the alternating N-type and P-type semiconductor regions. The metal foil is disposed on a plurality of metal seed material regions, and the metal foil has an anodized portion of the metal region of the metal foil that is insulated and corresponds to the alternating N-type and P-type semiconductor regions.

Description

Foil-based metallization of solar cells

Embodiments of the present invention belong to the field of renewable energy, and particularly include a foil-based metallization method including a solar cell, and a solar cell obtained by the method.

Photovoltaic cells, commonly known as solar cells, are well-known devices used to directly convert solar radiation into electrical energy. Generally speaking, a solar cell uses a semiconductor process technology to form a p-n junction close to the surface of a substrate for manufacturing on a semiconductor wafer or substrate. The solar radiation that hits the surface of the substrate and enters the substrate generates electron and hole pairs in the bulk substrate. The electron and hole pairs move to the p-doped and n-doped regions in the substrate, thereby generating a voltage difference between the doped regions. The doped region is connected to a conductive region on the solar cell to direct current from the cell to an external circuit coupled thereto.

Efficiency is an important characteristic of solar cells because it is directly related to the ability of solar cells to generate electricity. Similarly, the efficiency of producing solar cells is directly related to the cost-effectiveness of such solar cells. Accordingly, a technology for increasing the efficiency of a solar cell or a technology for increasing the production efficiency of a solar cell is generally desired. Some embodiments of the present invention allow the production efficiency of solar cells to be increased by providing a novel process for manufacturing solar cell structures. Some embodiments of the present disclosure allow increasing solar cell efficiency by providing a novel solar cell structure.

In one embodiment, a method for manufacturing a solar cell includes forming a plurality of alternating N-type and P-type semiconductor regions in a substrate or on a substrate. The method also includes attaching a metal foil to alternating N-type and P-type semiconductor regions. The method also includes only laser ablation through a portion of the metal foil that passes through a region corresponding to a location between alternate N-type and P-type semiconductor regions. The method also includes, after laser ablation, insulating the remaining metal foil regions corresponding to alternating N-type and P-type semiconductor regions.

In one embodiment, the insulating residual metal foil region includes anodized residual metal foil.

In one embodiment, the insulating residual metal foil region includes an etched residual metal foil.

In one embodiment, the method further includes, before attaching the metal foil, forming a plurality of metal seed material regions to provide metal seed material regions on each of the alternating N-type and P-type semiconductor regions, wherein the metal is attached The foil in the alternating N-type and P-type semiconductor regions includes attaching a metal foil to a plurality of metal seed material regions.

In one embodiment, the method further comprises, before attaching the metal foil to the plurality of metal seed material regions, forming an insulating layer on the plurality of metal seed material regions, wherein the metal foil is attached to the plurality of metal seed materials. The area contains the area that breaks the insulation layer.

In one embodiment, attaching the metal foil to the plurality of metal seed material regions includes using a technique selected from the group consisting of a laser welding process, a hot pressing process, and an ultrasonic bonding process.

In one embodiment, forming the plurality of metal seed material regions includes forming aluminum regions each having a thickness of about 0.3 to 20 micrometers, which includes an amount of about 97% or more of aluminum and an amount of silicon in a range of about 0-2%. , Wherein the attached metal foil includes an aluminum foil having a thickness in the range of about 5-100 micrometers, and the area of the remaining metal foil in the insulation includes the exposed surface of the aluminum oxide foil to a depth in the range of about 1-20 micrometers, Take anodized aluminum foil.

In one embodiment, only the portion where the laser ablation passes through the metal foil includes a thickness in the range of approximately 80-99% of the thickness of the complete metal foil of the laser ablated metal foil.

In one embodiment, forming a plurality of alternating N-type and P-type semiconductor regions includes alternating N-type and P-type semiconductor regions in a polycrystalline silicon layer formed on a substrate, and the method further includes forming a trench Between each of the alternating N-type and P-type semiconductor regions, the trench partially extends into the substrate.

In one embodiment, the substrate is a single crystal silicon substrate, and forming a plurality of alternating N-type and P-type semiconductor regions includes forming the alternating N-type and P-type semiconductor regions in the single crystal silicon substrate.

In one embodiment, the method further includes forming a masking layer on at least a portion of the metal foil before the laser ablation.

In one embodiment, a method for manufacturing a solar cell includes forming a plurality of alternating N-type and P-type semiconductor regions in a substrate or on a substrate. The method also includes attaching anodized metal foil to alternating N-type and P-type semiconductor regions. The anodized metal foil has an anodized top surface and an anodized bottom surface with a metal portion therebetween, wherein an anodized metal foil is attached The wafer in alternating N-type and P-type semiconductor regions includes an anodized bottom surface region that breaks anodized metal foil. Methods also include laser ablation through and alternating between N-type and P-type semiconductor regions. The anodized top surface and metal part of the anodized metal foil in the area corresponding to the position, where the laser ablation ends at the anodized metal foil of the remaining metal foil corresponding to the alternating N-type and P-type semiconductor regions Anodized bottom surface of the insulation area.

In one embodiment, the method further comprises, before attaching the anodized metal foil, forming a plurality of metal seed material regions to provide metal seed material regions on each of the alternating N-type and P-type semiconductor regions, wherein Attaching the anodized metal foil to the alternating N-type and P-type semiconductor regions includes attaching the anodized metal foil to a plurality of metal seed material regions.

In one embodiment, the method further comprises, before attaching the anodized metal foil to the plurality of metal seed material regions, forming an insulating layer on the plurality of metal seed material regions, wherein the anodized metal foil is attached to the plurality of metal seed material regions. The metal seed material region contains a region that breaks the insulation layer.

In one embodiment, attaching the anodized metal foil to the plurality of metal seed material regions includes using a technique selected from the group consisting of a laser welding process, a hot pressing process, and an ultrasonic bonding process.

In one embodiment, forming the plurality of metal seed material regions includes forming aluminum regions each having a thickness of about 0.3 to 20 micrometers, which includes an amount of about 97% or more of aluminum and an amount of silicon in a range of about 0-2%. Where the anodized metal foil is attached including anodized aluminum foil with an anodized top surface and an anodized bottom surface having a total thickness in the range of about 5-100 microns, each including a thickness in the range of about 1-20 microns sheet.

In one embodiment, the method further includes forming a laser reflective or absorbing film on the anodized bottom surface of the anodized metal foil before attaching the anodized metal foil to the alternating N-type and P-type semiconductor regions. .

In one embodiment, forming a plurality of alternating N-type and P-type semiconductor regions is included in a polycrystalline silicon layer formed on a substrate, forming alternating N-type and P-type semiconductor regions, and the method further includes forming A trench between each of the alternating N-type and P-type semiconductor regions, the trench partially extending into the substrate.

In one embodiment, the substrate is a single crystal silicon substrate, and forming a plurality of alternating N-type and P-type semiconductor regions includes forming the alternating N-type and P-type semiconductor regions in the single crystal silicon substrate.

In one embodiment, the method further includes forming a masking layer on a portion of the anodized metal foil before laser ablation, and removing the masking layer after laser ablation.

In one embodiment, the solar cell includes a substrate. A plurality of alternating N-type and P-type semiconductor regions are disposed in or on the substrate. The conductive contact structure is provided on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a metal seed material region provided on each of the alternating N-type and P-type semiconductor regions. A plurality of metal seed material regions, and a metal foil provided on the plurality of metal seed material regions, the metal foil having insulation and the metal regions of the metal foil corresponding to alternating N-type and P-type semiconductor regions; Anodized section.

In one such embodiment, the exposed surfaces of all metal foils are anodized.

100, 300, 500, 600, 650‧‧‧ substrates

102, 302‧‧‧ thin dielectric layer

104, 304, 604, 654‧‧‧ N-type semiconductor regions

106, 306, 606, 656‧‧‧P-type semiconductor regions

108, 308‧‧‧ trench

110‧‧‧Bottom anti-reflective coating (BARC) material

112, 312‧‧‧Anti-reflective coating (ARC)

114, 314, 514, 614, 664‧‧‧ metal seed material area

116‧‧‧Insulation

118, 618, 668‧‧‧ metal foil

120, 320‧‧‧ metal solder joints

122, 322, 522‧‧‧ groove

124, 624‧‧‧oxide coating

126‧‧‧Location

128‧‧‧ opening

200, 400‧‧‧ flowchart

202, 204, 206, 208, 210, 402, 404, 406, 408‧‧‧ operation

101, 301‧‧‧ light receiving surface

318‧‧‧ Anodized metal foil

319‧‧‧ alumina coating

319A‧‧‧Anodized top surface

319B‧‧‧Anodized bottom surface

518‧‧‧Foil

520‧‧‧welding point

669‧‧‧Anodized part

Figures 1A to 1E depict cross-sectional views of various stages in the manufacture of a solar cell using foil-based metallization according to an embodiment of the present invention, where: FIG. 1A depicts the stage after the selective metal seed region is formed on the emitter region formed on a part of the back surface of the solar cell substrate in the manufacture of the solar cell; FIG. 1B depicts the first stage after the selective formation of the protective layer Figure 1C; Figure 1C depicts the structure of Figure 1B after the metal foil is attached to its back; Figure 1D depicts the structure of Figure 1C after the laser groove is formed in the metal foil; and Figure 1E Structure depicting Figure 1D after the exposed surface of the anodized metal foil.

FIG. 2 is a flowchart illustrating operations corresponding to FIGS. 1A to 1E in the method for manufacturing a solar cell according to the embodiment of the present invention.

3A to 3C depict cross-sectional views of various stages in the manufacture of a solar cell using a foil-based metallization according to another embodiment of the present invention, wherein: FIG. 3A depicts the manufacturing of a solar cell, which involves Stage of placing anodized metal foil on a selective metal seed region formed on an emitter region formed on a part of the back surface of a solar cell substrate; FIG. 3B depicts the welding of the anodized metal foil to its back surface 3A; and FIG. 3C depicts the structure of FIG. 3B after the laser grooves are formed in the anodized metal foil.

FIG. 4 is a flowchart illustrating operations corresponding to FIGS. 3A to 3C in the method for manufacturing a solar cell according to the embodiment of the present invention.

FIG. 5 depicts a cross-sectional view of each stage in the manufacture of another solar cell using anodized foil as a base metallization according to another embodiment of the present invention.

FIG. 6A depicts a cross-sectional view of a portion of a solar cell having a foil-based contact structure formed on an emitter region formed in a substrate according to an embodiment of the present invention.

FIG. 6B depicts a cross-sectional view of a portion of a solar cell having an anodized foil-based contact structure formed on an emitter region formed in a substrate according to an embodiment of the present invention.

The following detailed description is for illustrative purposes only and is not intended to limit the subject matter of the application or the application and use of such embodiments. As used herein, the word "exemplary" means "used as an example, instance, or illustration." Any implementation described herein as exemplary is not necessarily to be construed as preferred or superior to other implementations. In addition, it is not intended to be bound by theory presented or implied in the foregoing technical field, background, summary, or detailed description below.

This specification includes references to "one embodiment" or "an embodiment". The appearances of the phrases "in one embodiment" and "in an embodiment" do not necessarily denote the same embodiment. Specific features, structures, or characteristics may be combined in any suitable manner consistent with the present invention.

Terminology, the following paragraphs provide definitions and / or contents of the terms found in the present invention (including the scope of the attached patent application): "Comprising", this term is open ended. This term does not exclude other structures or steps when used in the scope of the attached patent application.

"Configured to", various units or components can be described or claimed as "configured to" perform one or more tasks. In such contexts, "configure to" is used to imply a structure by indicating that a unit / component contains a structure that performs those one or more tasks during operation. Thus, even when a particular unit / component is not currently operating (eg, not on / active), the unit / component can be said to be configured to work. It is described that a unit / circuit / component is "configured to" perform one or more tasks specifically for the unit / component, and is not intended to invoke 35 U.S.C. § 112, paragraph 6.

"First", "Second", etc., as used herein, these terms are used as labels for the nouns they prefix, and do not imply any sort of ordering (e.g., space, Time, logic, etc.). For example, referring to a "first" solar cell does not necessarily mean that the solar cell is the first solar cell in sequence; on the contrary, the term "first" is used to distinguish another solar cell (for example, "second "Solar cells) and this solar cell.

"Coupled"-The following description indicates that components or nodes or features are "coupled" together. As used herein, unless expressly stated otherwise, "coupled" means that one element / node / feature is directly or indirectly connected to (or directly or indirectly communicates with) another element / node / feature. , Not necessarily mechanical.

In addition, some terms may be used in the following description for reference purposes only, and thus are not intended to be limiting. For example, terms such as "upper", "lower", "above" and "below" indicate directions in a drawing to be referred to. Terms such as "front", "back", "rear", "side", "outboard" and "inboard" are described by referring to the following discussion The text and related drawings of the components are described in the direction and / or location of the component parts in a consistent but arbitrary framework that becomes clear for reference. Such terms may include words specifically mentioned above, derivatives thereof, and words of similar meaning.

This article describes a foil-based metallization method for solar cells and the resulting solar cells. In the following description, many specific details are described, such as specific operating procedures, to provide a thorough understanding of the embodiments of the present invention. It will be apparent to those of ordinary skill in the art that the disclosed embodiments may be performed without such specific details. In other examples, conventional manufacturing techniques, such as lithography and patterning techniques, are not described in detail to avoid unnecessarily obscuring the embodiments of the present disclosure. In addition, it will be understood that the various embodiments shown in the drawings are illustrative and not necessarily drawn to scale.

This article discloses a method for manufacturing a solar cell. In one embodiment, a method for manufacturing a solar cell involves forming a plurality of alternating N-type and P-type semiconductor regions in a substrate or on a substrate. The method also involves attaching a metal foil to alternating N-type and P-type semiconductor regions. The method also involves only laser ablation through the metal foil in the area corresponding to the location between the alternating N-type and P-type semiconductor regions Pieces of tablets. The method also involves, after laser ablation, anodizing the remaining metal foil to insulate regions of the remaining metal foil corresponding to alternating N-type and P-type semiconductor regions.

In another embodiment, a method for manufacturing a solar cell involves forming a plurality of alternating N-type and P-type semiconductor regions in a substrate or on a substrate. The method also involves attaching anodized metal foils to alternating N-type and P-type semiconductor regions. The anodized metal foil has an anodized top surface and an anodized bottom surface with a metal portion therebetween. Attaching the anodized metal foil to the alternating N-type and P-type semiconductor regions involves breaking the anodized bottom surface area of the anodized metal foil. The method also involves laser ablation through the anodized top surface of the anodized metal foil and the metal portion of the anodized metal foil through the area corresponding to the locations between the alternating N-type and P-type semiconductor regions. Laser ablation ends on the anodized bottom surface of the remaining metal foil corresponding to the alternating N-type and P-type semiconductor regions, which is the anodized metal foil insulation region.

This article also discloses solar cells. In one embodiment, the solar cell includes a substrate. A plurality of alternating N-type and P-type semiconductor regions are disposed in or on the substrate. The conductive contact structure is disposed on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions providing metal seed material regions disposed on each of the alternating N-type and P-type semiconductor regions. The metal foil is disposed on a plurality of metal seed material regions, and the metal foil has an anodized portion that is insulated from the metal regions of the metal foil corresponding to the alternating N-type and P-type semiconductor regions.

One or more embodiments described herein are directed to metallization of solar cells based on metal (such as aluminum) anodization. In one embodiment, an aluminum metallization process for an interdigitated back contact (IBC) solar cell is disclosed. In one embodiment, an anodizing and subsequent laser grooving method is disclosed.

In the first aspect, a laser engraving groove based on laser patterning and anodization of aluminum (Al) foil (which is laser welded to the battery) and subsequent anodizing processes provide a new electrode pattern for IBC solar cells Method to form contact fingers that cross each other. An embodiment of the first method may be performed to provide a non-destructive method for patterning Al foil on a wafer and avoid complicated alignment and / or masking methods.

Consistent with the first aspect of the above reference, FIGS. 1A to 1E depict cross-sectional views of various stages in the manufacture of a solar cell using foil-based metallization according to an embodiment of the present invention. FIG. 2 is a flowchart showing operations corresponding to FIGS. 1A to 1E in the method for manufacturing a solar cell according to the embodiment of the present invention.

FIG. 1A depicts the stage after the selective metal seed region is formed on the emitter region formed on a part of the back surface of the solar cell substrate in the manufacture of the solar cell. Referring to FIG. 1A and corresponding operation 202 of the flowchart 200, a plurality of alternating N-type and P-type semiconductor regions are formed on a substrate. Specifically, the substrate 100 has been provided thereon with an N-type semiconductor region 104 and a P-type semiconductor region 106 provided on the thin dielectric material 102, and the thin dielectric material 102 serves as the N-type semiconductor region 104 or P, respectively. An intermediate material between the -type semiconductor region 106 and the substrate 100. The substrate 100 has a light-receiving surface 101 opposite to the back surface on which the N-type semiconductor region 104 and the P-type semiconductor region 106 are formed.

In one embodiment, the substrate 100 is a single crystal silicon substrate, such as a single crystal N-type doped silicon substrate. However, what is correctly evaluated is that the substrate 100 may be a layer disposed on a substrate of a global solar cell, such as a polycrystalline silicon layer. In one embodiment, the thin dielectric layer 102 is a tunneling silicon oxide layer having a thickness of about 2 nm or less. In one such embodiment, the term "tunneling dielectric layer" means a very thin dielectric layer through which conduction can be achieved. Conduction may be due to the existence of quantum tunneling and / or small regions directly physically connected through thin spots of the dielectric layer. In one embodiment, the tunneling dielectric layer is or includes a thin silicon oxide layer.

In one embodiment, alternating N-type and P-type semiconductor regions 104 and 106 are formed as polycrystalline silicon, for example, by using plasma-assisted chemical vapor deposition (PECVD). In one such embodiment, the N-type polycrystalline silicon emitter region 104 is doped with N-type impurities, such as phosphorus. The P-type polycrystalline silicon emitter region 106 is doped with a P-type impurity, such as boron. As depicted in FIG. 1A, the alternating N-type and P-type semiconductor regions 104 and 106 may have trenches 108 formed therebetween, the trenches 108 partially extending into the substrate 100. In addition, in one embodiment, the bottom anti-reflection coating (BARC) material 110 or other protective layer (like Is an amorphous silicon layer) is formed on the alternating N-type and P-type semiconductor regions 104 and 106, as shown in FIG. 1A.

In an embodiment, the light receiving surface 101 is a textured light receiving surface, as shown in FIG. 1A. In one embodiment, a hydroxide-based wet etchant is used to texture the light receiving surface 101, if possible, and the surface of the trench 108 of the substrate 100, as also described in FIG. 1A. It will be correctly evaluated that the texturing time of the light receiving surface may vary. For example, texturing may be performed before or after the formation of the thin dielectric layer 102. In an embodiment, the textured surface may be a surface having a regular or irregular shape for scattering incident light and reducing the amount of light reflected from the light receiving surface 101 of the solar cell. Referring again to FIG. 1A, other embodiments may include the formation of a passivation and / or anti-reflective coating (ARC) layer (collectively shown as layer 112) on the light receiving surface 101. It will be correctly evaluated that the formation time of the passivation and / or ARC layer may also vary.

Referring again to FIG. 1A and now referring to the corresponding selective operation 204 of the flowchart 200, a plurality of metal seed material regions 114 are formed to provide metal seed material regions at each of the alternating N-type and P-type semiconductor regions 104 and 106 on. The metal seed material region 114 directly contacts the alternating N-type and P-type semiconductor regions 104 and 106.

In one embodiment, the metal seed region 114 is an aluminum region. In one such embodiment, the aluminum regions each have a thickness in the range of approximately 0.3 to 20 microns, and include approximately 97% or more of aluminum and silicon in the range of approximately 0-2%. In other embodiments, the metal seed region 114 includes a metal, such as nickel, silver, cobalt, or tungsten, but is not limited thereto.

FIG. 1B depicts the structure of FIG. 1A after the protective layer is selectively formed. In particular, referring to FIG. 1B, the insulating layer 116 is formed on the plurality of metal seed material regions 114. In one embodiment, the insulating layer 116 is a silicon nitride oxide silicon nitride material layer.

FIG. 1C depicts the structure of FIG. 1B after the metal foil is attached to its back surface. Referring to the corresponding operation 206 of FIG. 1C and the flowchart 200, by directly coupling the metal foil 118 and each metal seed material Corresponding portions of the region 114 are attached with metal foils 118 to alternate N-type and P-type semiconductor regions. In one such embodiment, the direct coupling of a portion of the metal foil 118 to a corresponding portion of the metal seed material region 114 involves forming a metal solder joint 120 at each of such locations, as depicted in FIG. 1C. Show. In another embodiment, the metal seed region 114 is replaced with a blanket metal seed layer that is not patterned at this stage of the process. In that embodiment, the blanket metal seed layer may be patterned during a subsequent etching process, such as during a hydroxide-based wet etching process.

In one embodiment, the metal foil 118 is an aluminum (Al) foil having a thickness in a range of about 5-100 micrometers, and preferably a thickness in a range of 50-100 micrometers. In one embodiment, the aluminum foil is an aluminum alloy foil, which includes aluminum and a second element, such as copper, manganese, silicon, magnesium, zinc, tin, lithium, or a combination thereof, but is not limited thereto. In one embodiment, the aluminum foil is, for example, F-grade (as fabricated), O-grade (full soft), H-grade (strain hardened), or T-grade ( (Heat treatment), but is not limited to temper grade foil.

In one embodiment, the metal foil 118 is directly attached to the plurality of metal seed material regions 114 by a technique such as a laser welding process, a hot pressing process, or an ultrasonic bonding process, but is not limited thereto. In one embodiment, the selective insulation layer 116 is included, and the attachment of the metal foil 118 to the plurality of metal seed material regions 114 involves breaking the insulation layer 116, as shown in FIG. 1C.

It will be correctly evaluated that, according to other embodiments, a seedless method may be implemented. In one such embodiment, the metal seed material region 114 is not formed, and the metal foil 118 is directly attached to the material of the alternating N-type and P-type semiconductor regions 104 and 106. For example, in one embodiment, the metal foil 118 is directly attached to the alternating N-type and P-type polycrystalline silicon regions.

FIG. 1D depicts the structure of FIG. 1C after the laser groove is formed in the metal foil. Referring to the corresponding operation 208 of FIG. 1D and flowchart 200, the metal foil 118 is ablated by the laser and passes through the metal foil of the region corresponding only to the positions between the alternate N-type and P-type semiconductor regions 104 and 106 118, for example, in The position of the trench 108 shown in FIG. 1D is shown. The laser ablation forms a groove 122, which partially extends into the metal foil 118, but does not completely penetrate the metal foil 118.

In one embodiment, forming the laser groove 122 involves laser ablating the thickness of the metal foil 118 in a range of approximately 80-99% of the thickness of the complete metal foil 118. In such an embodiment, the key point is that the lower portion of the metal foil 118 is not penetrated, so that the metal foil 118 protects the underlying emitter structure.

In one embodiment, the laser ablation is performed without a mask; however, in other embodiments, the mask layer is formed on the portion of the metal foil 118 before the laser ablation, and after the laser ablation Was removed. In one such embodiment, the mask is formed over a portion or the entire foil area. In another embodiment, the mask is left in place during the anodizing process described below. In one embodiment, the mask is not removed at the end of the process. However, in another embodiment, the mask is not removed at the end of the process and the mask is retained as a protective layer.

Figure 1E depicts the structure of Figure 1D after the exposed surface of the anodized metal foil. Referring to FIG. 1E and the corresponding operation 210 of the flowchart 200, the remaining metal foil 118 is anodized on its exposed surface to replace the remaining metal foils corresponding to the alternating N-type and P-type semiconductor regions 104 and 106 Area 118 is insulated. In particular, the exposed surface of the metal foil 118, including the surface of the groove 122, is anodized to form an oxide coating 124. At the position 126 corresponding to the alternating N-type and P-type semiconductor regions 104 and 106, such as the groove 122 above the trench 108, the entire remaining thickness of the metal foil 118 is anodized, so that the insulation remains in each Areas of the metal foil 118 above the N-type and P-type semiconductor regions 104 and 106.

In one embodiment, the metal foil 118 is an aluminum foil, and anodizing the metal foil involves forming alumina on the exposed and outermost areas of the remaining portion of the metal foil 118. In one such embodiment, the anodized aluminum foil involves the exposed surface of the aluminum oxide foil to a depth in the range of about 1-20 microns, and preferably a depth in the range of about 5-20 microns. In an embodiment, in order to electrically insulate the contact portion of the metal foil 118, the portion of the metal foil 118 at the bottom of the laser groove 122 is completely anodized, such as Illustrated in Figure 1E. In one embodiment, the opening 128 may be formed in a portion of the oxide coating 124, as also shown in FIG. 1E to enable access to certain areas of the metal foil 118.

Referring to FIG. 1E again, in another embodiment, the patterned metal foil is etched to replace the portion of the anodized metal foil to insulate the metal foil with a portion of the insulating metal foil. In one such embodiment, the structure of FIG. 1D is exposed to a wet etchant. Although the wet etchant etched all exposed portions of the metal foil, a carefully timed etching process was used to break the bottom of the laser groove 122 without significantly reducing the thickness of the non-grooved area of the metal foil. In a specific embodiment, a hydroxide-based etchant such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) is used, but is not limited thereto.

In a second aspect, the anodizing and subsequent laser grooving methods involve the implementation of anodized foil using anodized aluminum oxide (AAO) as the laser landing zone. The landing zone is then reserved to provide electrical insulation in the final solar cell.

Consistent with the second aspect of the above reference, FIGS. 3A to 3C depict cross-sectional views of various stages in the manufacture of a solar cell using a foil-based metallization according to another embodiment of the present invention. FIG. 4 is a flowchart illustrating operations corresponding to FIGS. 3A to 3C in the method for manufacturing a solar cell according to the embodiment of the present invention.

FIG. 3A depicts a stage in the manufacture of a solar cell which involves placing an anodized metal foil on a selective metal seed region formed on an emitter region formed on a part of a back surface of a solar cell substrate. Referring to FIG. 3A and corresponding operation 402 of the flowchart 400, a plurality of alternating N-type and P-type semiconductor regions are formed on a substrate. Specifically, the substrate 300 has been provided thereon with an N-type semiconductor region 304 and a P-type semiconductor region 306 provided on the thin dielectric material 302, and the thin dielectric material 302 serves as the N-type semiconductor region 304 or P, respectively. An intermediate material between the -type semiconductor region 306 and the substrate 300. The substrate 300 has a light-receiving surface 301 opposite to the back surface on which the N-type semiconductor region 304 and the P-type semiconductor region 306 are formed.

In one embodiment, the substrate 300 is a single crystal silicon substrate, such as a bulk single crystal N-type doped silicon substrate. However, it will be correctly evaluated that the substrate 300 may be a layer disposed on the entire solar cell substrate, such as a polycrystalline silicon layer. In one embodiment, the thin dielectric layer 302 is a tunneling silicon oxide layer having a thickness of about 2 nm or less. In one such embodiment, the term "tunneling dielectric layer" means a very thin dielectric layer through which conduction can be achieved. Conduction may be due to the existence of quantum tunneling and / or small regions directly physically connected through thin spots of the dielectric layer. In one embodiment, the tunneling dielectric layer is or includes a thin silicon oxide layer.

In one embodiment, alternating N-type and P-type semiconductor regions 304 and 306 are formed as polycrystalline silicon, for example, by using plasma-assisted chemical vapor deposition (PECVD). In one such embodiment, the N-type polycrystalline silicon emitter region 304 is doped with N-type impurities, such as phosphorus. The P-type polycrystalline silicon emitter region 306 is doped with a P-type impurity, such as boron. As depicted in FIG. 3A, the alternating N-type and P-type semiconductor regions 304 and 306 may have a trench 308 formed therebetween, the trench 308 partially extending into the substrate 300.

In one embodiment, the light receiving surface 301 is a textured light receiving surface, as shown in FIG. 3A. In one embodiment, a hydroxide-based wet etchant is used to texture the light receiving surface 301, if possible, and the surface of the trench 308 of the substrate 300, as also described in FIG. 3A. It will be correctly evaluated that the texturing time of the light receiving surface may vary. For example, texturing may be performed before or after the formation of the thin dielectric layer 302. In an embodiment, the textured surface may be a surface having a regular or irregular shape for scattering incident light and reducing the amount of light reflected from the light receiving surface 301 of the solar cell. Referring again to FIG. 3A, other embodiments may include the formation of a passivation and / or anti-reflective coating (ARC) layer (collectively shown as layer 312) on the light receiving surface 301. It will be correctly evaluated that the formation time of the passivation and / or ARC layer may also vary.

Referring again to FIG. 3A and now referring to the corresponding selective operation 404 of the flowchart 400, a plurality of metal seed material regions 314 are formed to provide metal seed material regions in alternate N-types, respectively. And P-type semiconductor regions 304 and 306. The metal seed material region 314 directly contacts the alternating N-type and P-type semiconductor regions 304 and 306.

In one embodiment, the metal seed region 314 is an aluminum region. In one such embodiment, the aluminum regions each have a thickness in the range of approximately 0.3 to 20 microns, and include aluminum in an amount of approximately 97% or more and silicon in an amount of approximately 0-2%. In other embodiments, the metal seed region 314 includes a metal, such as nickel, silver, cobalt, or tungsten, but is not limited thereto.

Referring again to FIG. 3A, the anodized metal foil 318 is placed over the metal seed region 314. In one embodiment, the anodized metal foil 318 is an anodized aluminum foil having an aluminum oxide coating 319 formed thereon. In one such embodiment, the anodized metal foil 318 has a total thickness in the range of about 5-100 microns, and preferably a total thickness in the range of 50-100 microns, including the anodized top surface 319A and the anode. The bottom surface 319B each has a thickness in the range of approximately 1-20 microns, and preferably a thickness in the range of 5-20 microns. Therefore, in one embodiment, the anodized metal foil 318 has an anodized top surface (coating 319A) and an anodized bottom surface (coating 319B) including a conductive metal portion therebetween. In an embodiment, the anodized metal foil 318 is an anodized aluminum foil, which includes aluminum and a second element, such as copper, manganese, silicon, magnesium, zinc, tin, lithium, or a combination thereof, but is not limited to this. In one embodiment, the anodized metal foil 318 is a tempered anodized such as F-grade (for manufacturing), O-grade (all soft), H-grade (strain hardening), or T-grade (heat treatment). Aluminum foil, but not limited to this.

FIG. 3B depicts the structure of FIG. 3A after the anodized metal foil is welded to its back surface. Referring to the corresponding operation 406 of FIG. 3B and the flowchart 400, the anodized metal foil 318 is attached to the alternating N-type and P-type semiconductor regions 304 and 306. In one such embodiment, the direct coupling of a portion of the anodized metal foil 318 to a portion corresponding to the metal seed material region 314 involves forming a metal solder joint 320 at each of such locations, as shown in FIG. 3B Illustrated. In a specific embodiment, after the spot welding matrix, the anodized metal foil 318 is flattened on the back surface by a vacuum system and laser welded to the metal seed layer.

In one embodiment, the anodized metal foil 318 is attached to the plurality of metal seed material regions 314 by using a technique such as a laser welding process, a hot pressing process, or an ultrasonic bonding process, but is not limited thereto. In one embodiment, attaching the anodized metal foil 318 to the plurality of metal seed material regions 314 involves breaking the oxidized coating 319B on the bottom surface, as shown in FIG. 3B.

In one embodiment (not shown, but similar to the description in FIG. 1B), before attaching the anodized metal foil 318 to the plurality of metal seed material regions 314, an insulating layer is formed on the plurality of metal seed material regions. 314 on. In that embodiment, attaching the anodized metal foil 318 to the plurality of metal seed material regions 314 involves breaking intervening regions of the insulating layer.

It will be correctly evaluated that, according to other embodiments, a seedless method may be implemented. In one such embodiment, the metal seed material region 314 is not formed, and the anodized metal foil 318 is directly attached to the material of the alternating N-type and P-type semiconductor regions 304 and 306. For example, in one embodiment, the anodized metal foil 318 is directly attached to the alternating N-type and P-type polycrystalline silicon regions. In one such embodiment, the process involves breaking the oxide coating 319B on the bottom surface.

FIG. 3C depicts the structure of FIG. 3B after the laser grooves are formed in the anodized metal foil. Referring to FIG. 3C and corresponding operation 408 of flowchart 400, the anodized metal foil 318 is ablated by the laser through the anodized top surface 319A, and between the alternate N-type and P-type semiconductor regions 304 and 306. The central metal portion of the anodized metal foil 318 in the region corresponding to the position is, for example, at the position of the groove 308 shown in FIG. 3C. Laser ablation ends at the anodized bottom surface 319B of the anodized metal foil 318, which is an insulating region of the remaining metal foil 318 corresponding to the alternating N-type and P-type semiconductor regions.

As a result, the laser ablation forms a groove 322, which partially extends into the anodized metal foil 318, but does not completely penetrate. In one embodiment, the key is that the anodized bottom surface 319B of the anodized metal foil 318 is not penetrated, so that the anodized metal foil 318 protects the underlying emitter structure. As a result, the groove depth is accurately controlled to sit on the bottom oxide layer of the anodized aluminum foil without completely cutting it. In one embodiment, laser ablation is performed without a mask; however, in other embodiments, The mask layer is formed on the portion of the anodized metal foil 318 before the laser ablation, and is removed after the laser ablation.

In one embodiment, the method described with reference to FIGS. 3A to 3C further involves forming a laser reflection or The absorption film is on the anodized bottom surface 319B of the anodized metal foil 318. In one embodiment, laser ablation involves the use of infrared (IR) lasers, and forming a laser reflective or absorbing film involves forming a magenta film. More broadly, what will be properly evaluated is that the embodiments involve the use of films that are designed based on the laser used. In this method, the color of the film is selected with the goal of reflection or ablation. In one specific embodiment, a magenta film is used to indicate that it absorbs green and reflects blue and red. In one embodiment, a top film that is transparent to laser light is applied to the upper surface of the anodized metal foil. However, a reflective film is used for the bottom surface of the anodized metal foil. In another embodiment, the bottom surface is a dyed anodized alumina layer that can absorb about 85% or more of the laser pulse.

Referring again to FIG. 3C, the laser is used to pattern the anodized aluminum foil in the final pattern. By forming grooves according to the cross pattern, it can be parallel or perpendicular to the seed pattern. The foregoing description confirms the general method and can be used directly for parallel grooves. In another embodiment, the method of roughening the insulation surface of the anodized aluminum foil on the rough metal two (M2) can be a gain, that is, to scribe the groove vertically to connect only the contacts of the selected polarity. In one such embodiment, the anodized aluminum layer on the bottom of the foil only prevents shunting between relatively polar contact fingers and electrical contacts made by spot welding.

FIG. 5 depicts a cross-sectional view of each stage in the manufacture of another solar cell using anodized foil as a base metallization according to another embodiment of the present invention. Referring to part (a) of FIG. 5, the anodized aluminum foil 518 is mounted on a substrate 500 having a plurality of metal seed material regions 514 disposed thereon. Referring to part (b) of FIG. 5, laser welding is performed to form a welding point 520 with an attached foil 518 on the metal seed region 514. Referring to part (c) of FIG. 5, laser patterning is performed to provide a laser groove 512. In one embodiment, the pattern of the groove is a pattern perpendicular to the metal seed region 514. In one embodiment, the laser ablation stops on the anodized bottom surface of the metal foil 518.

The embodiments described herein can be used to make solar cells. In some embodiments, referring to FIGS. 1E and 3C, the solar cell includes a plurality of alternating N-type (104 or 304) and P-type (106 or 306) semiconductor regions disposed above the substrate 100 or 300. The conductive contact structure is disposed on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions 114 or 314 that provide metal seed material regions disposed on each of the alternating N-type and P-type semiconductor regions. The metal foil 118 or 318 is disposed on a plurality of metal seed material regions. The metal foil 118 or 318 has an anodized portion 124 or 319 and is insulated from the metal region of the metal foil 118 or 318 corresponding to the alternating N-type and P-type semiconductor regions. In one such embodiment, the exposed surfaces of all metal foils 118 or 113 are anodized. However, in another embodiment, for metal contacts, the opening 128 may be formed in the anodized portion, as described in conjunction with FIG. 1E. In yet another embodiment, the foil is anodized before laser ablation, and subsequent anodization is not performed. In that embodiment, the laser groove 322 may have an exposed non-anodized surface, as shown in Figure 3C. In an embodiment, the substrate 100 or 300 is an N-type single crystal silicon substrate, and a plurality of alternating N-type (104 or 304) and P-type (106 or 306) semiconductor regions are disposed in a polycrystalline silicon material disposed above the substrate. .

In yet another embodiment, the substrate is a single crystal silicon substrate, and alternate N-type and P-type semiconductor regions are formed in the single crystal silicon substrate. In a first example, FIG. 6A depicts a cross-sectional view of a portion of a solar cell having a foil-based contact structure formed on an emitter region formed in a substrate according to an embodiment of the present invention. Referring to FIG. 6A, the solar cell includes a plurality of alternating N-type 604 and P-type 606 semiconductor regions disposed in a substrate 600. The conductive contact structure is disposed on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions 614 provided on the metal seed material regions disposed on each of the alternating N-type and P-type semiconductor regions. A metal foil 618 is disposed on the plurality of metal seed material regions 614. The metal foil 618 has an anodized portion 624, and The metal regions of the metal foils 618 corresponding to the alternating N-type and P-type semiconductor regions 604 and 606 are respectively insulated.

In a second example, FIG. 6B depicts a cross-sectional view of a portion of a solar cell having an anodized foil-based contact structure formed on an emitter region formed in a substrate according to an embodiment of the present invention. Referring to FIG. 6B, the solar cell includes a plurality of alternating N-type 654 and P-type 656 semiconductor regions disposed in a substrate 650. The conductive contact structure is disposed on a plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes a plurality of metal seed material regions 664 that provide metal seed material regions disposed on each of the alternating N-type and P-type semiconductor regions. A metal foil 668 is disposed on the plurality of metal seed material regions 664. The metal foil 668 has an anodized portion 669 that insulates the metal regions of the metal foil 668 corresponding to the alternating N-type and P-type semiconductor regions 664 and 666, respectively.

In another aspect of the invention, other embodiments are provided that are based on the concepts described in connection with the above exemplary embodiments. As the most widespread consideration, back-contact solar cells typically require patterned metal of two polarities on the back of the solar cell. When pre-patterning metal is not feasible due to factors such as cost, complexity, or efficiency, the low-cost, low-material process of blanket metal usually prefers laser patterning.

For high-efficiency batteries, the patterned metal on the back of the battery usually has two requirements: (1) complete insulation of the metal, and (2) a damage-free process. For large-scale production, the process may require a high-volume process, such as an output of more than 500 wafers per hour. For complex patterns, the use of lasers to pattern thick (eg, greater than 1 micron) or highly reflective metals (eg, aluminum) on top of silicon can create a substantial yield issue in manufacturing. Yield problems can arise because the energy requirements of ablating thick and / or highly reflective metals at high rates require laser energy (eg, greater than 1 J / cm2) above the damage limit of the underlying emitter. Based on the need to completely insulate the metal, and changes in metal thickness and laser energy, metal patterning is often performed over-etching. In particular, there does not appear to be a single laser energy window at high throughput / low cost, which can completely remove metal and not expose extremely destructive laser beams.

According to an embodiment of the present invention, a method for patterning different metals is described. Furthermore, what will be correctly evaluated is that due to the interaction between the patterning process and metal bonding, the bonding method that considers combining the first or seed metal layer (M1) with the upper metal layer, such as foil (M2), is also considered. Is important. As described in more detail below, some bonding methods may enable different patterning options.

In one embodiment, the bonding to the vapor-deposited thin seed metal (M1), and therefore the difference in adhesion strength between the foils (M2) bonded to the bottom wafer of the device, is achieved according to a bonding method. Furthermore, different forms of failure models were observed during the adhesion test. For laser bonding, adhesion may depend on laser flux (energy per focus area). At lower fluxes, the adhesion between M1 and M2 is too weak and M2 can be easily separated. When the laser flux increases, the adhesion between the foil and the underlying M1 seed layer by welding becomes strong enough to tear the foil during the adhesion test. When the laser flux becomes higher, the underlying M1 layer becomes affected, and the bonding of the device M1 wafer is broken before the foil is torn off during the peel test. In one embodiment, in order to obtain the advantages of such different tearing modes, a spatially shaped laser beam is used in the laser bonding process. Laser light can have a higher intensity in the outer area (M1 tear-off range) and a lower intensity in the inside (M2 tear-off range). After welding, the foil (M2) can be torn off with M1, At the same time, the M2 / M1 area is left under the complete welding.

In another aspect, when the wet chemical etchant is used to complete the insulation after the groove, M1 can be exposed to the etchant for a long time. During this time, unwanted etching may occur, or if M1 and M2 are not completely bonded together, chemicals may remain between the M1 and M2 poles. In both cases, if the aluminum foil is bonded to the metal seed layer along the metal fingers using a discontinuous bonding method (e.g., low density bonding, such as every 10 mm), the etchant may penetrate the foil / metal seed Interface, causing unnecessary M1 finger etch and / or M1 / M2 bonding damage, resulting in poor device performance. The bonding method may include laser welding, local thermo-compression bonding, soldering bonding, and ultra-sonic bonding. Therefore, not all parties All methods are compatible with etching-based patterning, and in particular any low-density bonding method, such as laser welding, can become particularly challenging.

In one embodiment, by protecting the M1 layer from chemical damage and allowing the use of an etching-based patterning process, the described method can be performed to solve the aforementioned problems associated with wet chemical etchant. Embodiments may include the use of laser welding as a bonding method and the use of chemical etching after laser engraving as a patterning method, but the concept can be applied to other non-linear bonding methods and chemical etching-based patterning .

In a first such embodiment, the blanket protective layer is deposited on the substrate after the metal seed is deposited, or is deposited on the foil before the laser welding process. The choice of material and layer thickness ensure that laser welding can be achieved through the protective layer. The material may be resistant to chemical etching processes (eg, potassium hydroxide (KOH) solution). Examples of suitable materials include, but are not limited to, adhesives, silicones, polymers, or thin dielectrics. In a second such embodiment, a thin cover layer (e.g., about 100 nanometers thick) is deposited on top of the metal seed layer. The thin cover layer is composed of a different metal (for example, Ni) and is a chemically resistant etching solution. In a specific embodiment, the thin cover layer is compatible with laser welding between M1 and M2. In a third such embodiment, before or after laser welding, the tentacles of the anti-etching material are printed between the M1 tentacles and heat treated to ensure continuous adhesion between the protective tentacles and the M2 foil. In a specific embodiment, the heat generated by the laser process is finally used to bond the protective material to the M2 layer. The interface between the foil and the fingers serves as a barrier against the etching solution. The material may be thin and / or soft enough so as not to affect the foil assembly and laser welding process (for example, close contact of M1 / M2 is necessary).

In the first exemplary process flow, the groove and etching method involves M1 being deposited on the device side of the solar cell (eg, deposition of a seed conductive layer capable of bonding to M2). The M2 layer is applied to the M1 / cell and maintains contact suitable for bonding. Applying bonding energy, such as heat pressing or laser energy (eg, long pulse duration (greater than 100 microseconds)) to locally heat M2, and bonding M1 and M2. The groove is then formed mechanically or by another laser process (e.g., short pulse duration, less than about 1 microsecond) To provide deep grooves (eg, more than about 80% of the foil thickness) and trim the foil from the foil loader. Insulation following the conductive region is achieved, for example, by applying an etching medium to the structure and selectively etching the remainder of M2. In one embodiment, in order to increase the selectivity, the pre-patterned M1 layer is selected to provide etching resistance to the etching medium, such as Ni metal resisting KOH etching. Potential M2 materials include, but are not limited to, aluminum, nickel, copper, titanium, chromium, or multilayer combinations thereof. For the aluminum M1 layer, the etching medium may include an alkaline chemical such as potassium hydroxide, or an acid chemical such as phosphoric acid or a mixture of phosphoric acid and nitric acid. The etching medium is then thoroughly cleaned from the wafer to complete the etching reaction and to avoid residual chemical residues on the wafer. Chemicals can be completely removed from the wafer using horizontal spray cleaning and / or sonic agitation.

In a second exemplary process flow, two-step patterning is used based on a high-power laser engraved slot and low-power laser insulation. The first method involves the deposition of M1 on the device side of the solar cell (for example, a seed conductive layer suitable for welding with M2 lasers) and the patterning of the deposited M1 layer. The M2 layer is then applied to the M1 / cell and maintains direct contact suitable for laser welding. A high-energy beam (eg, a long pulse duration (about greater than 100 microseconds) laser or electron beam) is applied to locally heat M2, and join M1 and M2. Other lasers are applied (eg, short pulse durations, less than about 1 microsecond) to provide deep grooves (eg, more than about 80% of the foil thickness) and trim the foil from the foil loader. A second low power laser is then applied along the laser groove to insulate the remaining M2.

It will be correctly evaluated that the grooves can be achieved by other methods. For example, in another embodiment, the aforementioned grooves are formed by a mechanical process, such as a hard-tip tool array dragged across the surface, kissing cutting, CNC milling, ion milling, and ion milling. milling) or other cutting mechanisms, but not limited to this, instead of using a laser process.

What will be correctly evaluated is that the remaining metal can be removed by other methods. For example, in another embodiment, after the groove is formed, the remaining metal is removed by using electricity, for example, at a high current, and heated by resistance to burn off the remaining metal. In another embodiment, after the groove is formed, the remaining metal is removed by very light / low flux laser ablation. In another embodiment, after the groove is formed, the remaining Residual metal is removed by other etchings, such as plasma etching or back-sputter etching. In another embodiment, after the groove is formed, the remaining metal is grasped or attached to the area of the metal to be removed, and then the "grabbed" portion is "pulled away".

In a first embodiment of the tearing method to remove excess metal, two parallel grooves are formed, leaving a metal strip to be torn off, the metal strip having a width in the range of about 100 to 500 microns. In a second embodiment, the groove line extends to the outside of the solar cell to serve as a tear off point for a subsequent tearing process. In a third embodiment, prior to grooving, an M1 / M2 bonding method, such as a laser welding point (or wire), thermocompression welding, or other method is used, which provides more than cutting the M2 foil at the end. Stronger cut adhesion. In the fourth embodiment, the shape of the laser beam of the laser groove or laser-bonded laser beam is used to modify the mechanical properties of the metal, such as customizing the cooling method by adjusting the beam profile and modifying it based on time and temperature. Particle structure. In this method, a post-groove isolation process becomes easy. In one such embodiment, the Gaussian beam shape is distorted to invert the peaks so that the edge profile has higher energy and is used to form a wire bond. Higher local heating at the joint edges causes greater stress and changes in cooling profile, while the edges of the welded material have lower drop strength or less toughness than the body. In this case, the interface was the first to fail in the tearing process. In each of the four embodiments, the metal seed layer may be patterned before the groove is etched, or patterned after the groove is etched, and is preferably insulated along with the aforementioned slitting.

In other embodiments, the M1 layer is transparently deposited on M1 or M2, and has a cover layer, such as Ni, polymer, oxide or Thin adhesive to protect it from etchants. In other embodiments, a joint with a suitable high density (eg, 100% from top to bottom) is implemented to prevent the etchant from penetrating into the gap, and to avoid over-etching of M1. The joining can be achieved by integration with the block M2 (for example, linear welding, thermocompression welding).

Although certain materials have been described in detail with reference to FIGS. 1A to 1E, FIGS. 3A to 3C, FIG. 5, FIG. 6A, and FIG. 6B and other embodiments described above, some The materials can be easily replaced with other materials, and other such embodiments are still within the spirit and scope of the embodiments of the present invention. For example, in one embodiment, a different material substrate, such as a III-V material substrate, may be used instead of the silicon substrate. In other embodiments, the aforementioned method can be applied to manufacture other solar cells. For example, the manufacture of light emitting diodes (LEDs) can benefit from the methods described herein.

As such, the foil-based metallization method of solar cells and the resulting solar cells have been described.

Although specific embodiments have been described previously, even if only a single embodiment is described with respect to specific features, these embodiments are not intended to limit the scope of the disclosure. Unless otherwise stated, examples of features provided in the present invention are intended to be illustrative and not restrictive. The foregoing description is intended to cover such alternatives, modifications, and equivalents as would be apparent to a person of ordinary skill in the technical field having the benefit of the present invention.

The scope of the invention encompasses any feature or combination of features (explicitly or implicitly) disclosed herein, or any generalization thereof, whether or not it mitigates any or all of the issues addressed herein. Therefore, during the examination of this application (or an application claiming priority), a new patent application scope can be formulated into any such feature combination. In particular, referring to the scope of the attached patent application, the features from the dependent item can be combined with the features of the independent item, and the features from each independent item can be combined in any suitable manner, and not only listed in the scope of the attached patent application Specific combination.

Claims (30)

A method of manufacturing a solar cell, the method comprising: forming a plurality of alternating N-type and P-type semiconductor regions in or on a substrate; attaching a metal foil to the plurality of alternating N-types and P-type semiconductor region; only the portion of the metal foil that passes through the region corresponding to the positions between the alternating N-type and P-type semiconductor regions by laser ablation; and after laser ablation , The insulation corresponds to the remaining metal foil regions of the plurality of alternating N-type and P-type semiconductor regions. The method as described in item 1 of the scope of the patent application, wherein the remaining metal foil area of the insulation includes the anodized remaining metal foil. The method as described in item 1 of the patent application scope, wherein insulating the remaining metal foil area includes etching the remaining metal foil. The method as described in item 1 of the scope of the patent application further includes: before attaching the metal foil, forming a plurality of metal seed material regions to provide a metal seed material region in the plurality of alternating N-types and Ps -Each of the -type semiconductor regions, wherein attaching the metal foil to the plurality of alternating N-type and P-type semiconductor regions includes attaching the metal foil to the plurality of metal seed material regions. The method as described in item 4 of the patent application scope further comprises: forming an insulating layer on the plurality of metal seed material regions before attaching the metal foil to the plurality of metal seed material regions, wherein the The metal foil includes a region that breaks the insulating layer in the plurality of metal seed material regions. The method as described in item 4 of the patent application scope, wherein attaching the metal foil to the plurality of metal seed material areas includes using a technique selected from a laser welding process, a hot pressing process, and an ultrasonic wave Group formed by joining processes. The method as described in item 4 of the patent application range, wherein forming the plurality of metal seed material regions includes forming a plurality of aluminum regions each having a thickness of approximately 0.3 to 20 microns, and the plurality of aluminum regions includes approximately 97% or more The amount of aluminum and the amount of silicon in the range of about 0-2%, wherein attaching the metal foil includes attaching an aluminum foil having a thickness in the range of about 5-100 microns, and the remaining area of the metal foil in the insulation includes By oxidizing the exposed surface of the aluminum foil to a depth in the range of approximately 1-20 microns, the aluminum foil is anodized. The method as described in item 1 of the patent application scope, wherein only the portion of the laser ablation passing through the metal foil contains the metal foil with a laser ablation complete the thickness of the metal foil in the range of about 80-99% thickness of. The method of claim 1, wherein forming the plurality of alternating N-type and P-type semiconductor regions includes forming the plurality of alternating N-type and P-type semiconductor regions formed on the substrate In a polysilicon layer above, the method further includes forming a trench between each of the plurality of alternating N-type and P-type semiconductor regions, the trench partially extending into the substrate. The method as described in item 1 of the patent application range, wherein the substrate is a single crystal silicon substrate, and wherein forming the plurality of alternating N-type and P-type semiconductor regions includes forming the plurality of alternating N-type and The P-type semiconductor region is in the single crystal silicon substrate. The method as described in item 1 of the scope of the patent application further includes: before laser ablation, forming a mask layer on at least a portion of the metal foil. A method for manufacturing a solar cell, the method comprising: forming a plurality of alternating N-type and P-type semiconductor regions in or on a substrate; attaching an anodized metal foil to the plurality of alternating N- Type and P-type semiconductor regions, the anodized metal foil has an anodized top surface and an anodized bottom surface with a metal portion in between, wherein the anodized metal foil is attached to the plurality of alternating N- The type and P-type semiconductor regions include breaking the anodized bottom surface region of the anodized metal foil; and laser ablation through corresponding positions between the plurality of alternating N-type and P-type semiconductor regions The anodized top surface and the metal portion of the anodized metal foil of the region, where laser ablation ends with the remaining anodized metal foil corresponding to the plurality of alternating N-type and P-type semiconductor regions The anodized bottom surface of the insulated area of the anodized metal foil of the sheet. The method as described in item 12 of the patent application scope, further comprising: before attaching the anodized metal foil, forming a plurality of metal seed material regions to provide a metal seed material region in the plurality of alternating N-types And each of the P-type semiconductor regions, wherein attaching the anodized metal foil to the plurality of alternating N-type and P-type semiconductor regions includes attaching the anodized metal foil to the plurality of metal seed materials region. The method as described in item 13 of the patent application scope, further comprising: before attaching the anodized metal foil to the plurality of metal seed material regions, forming an insulating layer on the plurality of metal seed material regions, wherein Attaching the anodized metal foil to the plurality of metal seed material areas includes breaking the insulating layer area. The method as described in item 13 of the patent application range, wherein attaching the anodized metal foil to the plurality of metal seed material areas includes using a technique selected from a laser welding process, a hot pressing process, and a A group formed by ultrasonic bonding process. According to the method described in item 13 of the patent application scope, forming the plurality of metal seed material regions includes forming a plurality of aluminum regions each having a thickness of about 0.3 to 20 microns, and the plurality of aluminum regions includes an amount of about 97% or more Of aluminum with an amount of silicon in the range of about 0-2%, where attaching the anodized metal foil includes attaching an anodized aluminum foil with a total thickness in the range of about 5-100 microns, the anodized aluminum foil containing the The anodized top surface and the anodized bottom surface each have a thickness in the range of approximately 1-20 microns. The method as described in item 12 of the patent application scope further includes: forming a laser reflective film or a laser before attaching the anodized metal foil to the plurality of alternating N-type and P-type semiconductor regions The absorption film is on the anodized bottom surface of the anodized metal foil. The method as described in item 12 of the patent application range, wherein forming the plurality of alternating N-type and P-type semiconductor regions includes forming the plurality of alternating N-type and P-type semiconductor regions formed on the substrate In a polysilicon layer above, the method further includes forming a trench between each of the plurality of alternating N-type and P-type semiconductor regions, the trench partially extending into the substrate. The method as described in item 12 of the patent application range, wherein the substrate is a single crystal silicon substrate, and wherein forming the plurality of alternating N-type and P-type semiconductor regions includes forming the plurality of alternating N-type and The P-type semiconductor region is in the single crystal silicon substrate. The method as described in item 12 of the patent application scope further includes: before laser ablation, forming a mask layer on the portion of the anodized metal foil; and after laser ablation, removing the mask Floor. A solar cell, comprising: a substrate; a plurality of semiconductor regions disposed above the surface of the substrate, wherein individual semiconductor regions in the plurality of semiconductor regions are separated from each other by corresponding first regions in the plurality of first regions ; And a plurality of metal foil portions disposed above the plurality of semiconductor regions and electrically connected to the plurality of semiconductor regions; wherein the individual metal foil portions of the plurality of metal foil portions correspond to the plurality of semiconductor regions Individual semiconductor regions; wherein the individual metal foil portions of the plurality of metal foil portions are separated from each other by corresponding second regions in the plurality of second regions; and wherein the plurality of second regions are substantially separated from the The plurality of first regions above the surface of the substrate are aligned. The solar cell as described in Item 21 of the patent application range, wherein the plurality of metal foil portions are a plurality of aluminum foil portions. The solar cell according to item 21 of the patent application scope, further comprising: a plurality of metal seed material regions located on the plurality of semiconductor regions; wherein the individual metal seed material regions in the plurality of metal seed material regions Corresponding to individual semiconductor material regions of the plurality of semiconductor material regions; wherein the plurality of metal foil portions are located on the plurality of metal seed material regions; and wherein the individual metal foil portions of the plurality of metal foil portions Corresponding to the individual metal seed material regions in the plurality of metal seed material regions. The solar cell as described in item 23 of the patent application range, wherein the plurality of metal seed material regions include aluminum. The solar cell as described in item 24 of the patent application range, wherein the plurality of metal foil portions are a plurality of aluminum foil portions. The solar cell as described in item 23 of the patent application range, wherein the plurality of metal foils are partially spot welded to the plurality of metal seed material regions. The solar cell as described in item 21 of the patent application range, wherein at least a part of the outer surface of the plurality of metal foil portions is anodized. The solar cell as described in item 27 of the patent application range, wherein all exposed outer surfaces of the plurality of metal foil portions are anodized. The solar cell as described in item 21 of the patent application range, wherein the exposed outer surfaces of the plurality of metal foil portions are not anodized. The solar cell as described in item 21 of the patent application range, wherein the plurality of semiconductor regions include polycrystalline silicon.